Changed function generating names for uploaded files to the server.

src/Service/FileService.php

@@ -45,9 +45,13 @@ class FileService
 
     public function getFileName(File $file): string
     {
-        return 'ebook_' . $file->getBook()->getId() . '_' .
-            md5($file->getFileName()) . '.' .
-            $file->getExtension();
+        return sprintf(
+            'ebook_%d_%d_%s.%s',
+            $file->getBook()->getId(),
+            $file->getId(),
+            md5($file->getFileName()),
+            $file->getExtension()
+        );
     }
 
     /**